Process for joining stainless steel part and silicon carbide ceramic part and composite articles made by same

ABSTRACT

A process for joining a stainless steel part and a silicon carbide ceramic part comprising: providing a SUS part, a SiC ceramic part, a Mo foil and a Ti foil; placing the SiC ceramic part, the Mo foil, the Ti foil, and the SUS part into a mold, the Mo foil and the Ti foil located between the SiC ceramic part and the SUS part, the Mo foil abutting the SiC ceramic part, the Ti foil abutting the SUS part and the Mo foil; placing the mold into a chamber of an hot press sintering device, heating the chamber and pressing the SUS part, the SiC ceramic part, the Mo foil, and the Ti foil at least until the SUS part, the SiC ceramic part, the Mo foil and the Ti foil form a integral composite article.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to co-pending U.S. Patent Applications(Attorney Docket No.US36183), entitled “PROCESS FOR JOINING STAINLESSSTEEL PART AND TITANIUM CARBIDE CERAMIC PART AND COMPOSITE ARTICLES MADEBY SAME”. Such applications have the same assignee as the presentapplication. The above-identified applications are incorporated hereinby reference.

BACKGROUND

1. Technical Field

The present disclosure relates to a process for joining a metal part anda ceramic part, especially to a process for joining a stainless steelpart and a silicon carbide ceramic part, and a composite article made bythe process.

2. Description of the Related Art

Stainless steel has excellent corrosion resistance and abrasionresistance, and is widely applied in the components manufacturingindustry. However, unlike silicon carbide, stainless steel cannotmaintain its physical properties when used in an environment of hightemperature and strong corrosives. Therefore, a composite articlecomprising a stainless steel part and a silicon carbide ceramic part hasa desirable performance of high temperature resistance, corrosionresistance, abrasion resistance, and usable in extreme environments.

A typical process for joining stainless steel and silicon carbideceramic is by positioning one or more intermediate connecting layersbetween stainless steel and silicon carbide ceramic. However, due todiffering rates of heat expansion, the bond between the stainless steeland the silicon carbide ceramic is not as stable as desired.

Therefore, there is room for improvement within the art.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the embodiments can be better understood with referenceto the following drawings. The components in the drawings are notnecessarily drawn to scale, the emphasis instead being placed uponclearly illustrating the principles of the exemplary process for joiningstainless steel part and silicon carbide ceramic part, and compositearticle made by the process. Moreover, in the drawings like referencenumerals designate corresponding parts throughout the several views.Wherever possible, the same reference numbers are used throughout thedrawings to refer to the same or like elements of an embodiment.

FIG. 1 is a schematic cross-sectional view of an example of a hot presssintering device for implementing the present process.

FIG. 2 is a cross-sectional view of an exemplary embodiment of thepresent article made by the present process.

DETAILED DESCRIPTION

Referring to FIG. 1, an exemplary process for joining a stainless steelpart and a silicon carbide ceramic part, may includes the followingsteps:

A silicon carbide(SiC) ceramic part 20, a molybdenum(Mo) foil 40, atitanium(Ti) foil 50 and a stainless steel(SUS) part 30 are provided.The Mo foil 40 and the Ti foil 50 are used as a joining medium betweenthe SiC part 20 and the SUS part 30. The Mo foil 40 has a thickness in arange from about 0.1 millimeter (mm) to about 0.2 mm, the Ti foil 50 hasa thickness in a range from about 0.2 mm to about 0.4 mm.

The SiC ceramic part 20, the SUS part 30, the Mo foil 40 and the Ti foil50 are pretreated. The pretreatment may include the step of polishingthe surfaces of The SiC ceramic part 20, the SUS part 30, the Mo foil 40and the Ti foil 50 by sandpaper to produce smooth surfaces. Then, theSiC ceramic part 20, the SUS part 30, the Mo foil 40 and the Ti foil 50are cleaned by placing them into an organic solution to remove greasefrom their surfaces. The organic solution can be ethanol, and/or otherorganic solvents. Then, the SiC ceramic part 20, the SUS part 30, the Mofoil 40 and the Ti foil 50 are rinsed with water and dried.

A clamping mold 70 is used to hold the SiC ceramic part 20, the SUS part30, the Mo foil 40 and the Ti foil 50. The clamping mold 70 includes apressing board 72, a corresponding supporting board 74 and a receivingboard 76. The receiving board 76 defines a cavity 762 running throughthe upper/bottom surface to receive the SiC ceramic part 20, the SUSpart 30, the Mo foil 40 and the Ti foil 50. The pressing board 72 andthe corresponding supporting board 74 extend towards the cavity 762 fromopposing directions and can be moved relative to the cavity 762 by adriving system such as hydraulic pressure system. The SiC ceramic part20, the Mo foil 40, the Ti foil 50 and the SUS part 30 are placed intothe cavity 762 and clamped by the pressing board 72 and thecorresponding supporting board 74. The Mo foil 40 and the Ti foil 50 areinserted between the SiC ceramic part 20 and the SUS part 30. The Mofoil 40 abuts against the SiC ceramic part 20, the Ti foil 50 abutsagainst the SUS part 30. The pressing board 72 and the correspondingsupporting board 74 from two opposite sides, brings the surfaces of theparts to be joined into tight contact, for compressing the SiC ceramicpart 20, the Mo foil 40, the Ti foil 50 and the SUS part 30.

An hot press sintering device 100 including a chamber 101 is provided.The clamping mold 70 is placed into the chamber 101. The vacuum levelinside the chamber 101 is set to about 10⁻³Pa. Argon(Ar) is fed into thechamber 101 to maintain the chamber 101 pressure in a range of about0.3-0.6 MPa. The pressing board 72 and the corresponding supportingboard 74 press toward each other at about 10 Mpa to firmly clamp the SiCceramic part 20 and the SUS part 30. Then, the chamber 101 is heated ata rate of about 10-50 degrees Celsius per minute(° C./min). When thetemperature of the chamber 101 reaches to about 300° C., the clampingpressure applied by the boards 72,74 steadily increases, until thetemperature of the chamber 101 reaches to about 1000-1200° C., and theclamping pressure reaches to about 10-40 Mpa. The pressure and heat aremaintained in their respective peak ranges for about 30-60 min, so thatthe Mo foil 40 and the Ti foil 50 will interact with each other, and theMo foil 40 interacts with the SiC ceramic part 20, and the Ti foil 50interacts with the SUS part 30. Accordingly, the SiC ceramic part 20 andthe SUS part 30 are connected by the Mo foil 40 and the Ti foil 50 toform a composite article 10. The composite article 10 is removed afterthe chamber 101 is cooled.

Referring to FIG. 2, In the process of making the composite article 10,the Mo foil 40 and the Ti foil 50 act as intermediate layers to form aconnecting layer 80 that connect the SiC ceramic part 20 and the SUSpart 30. The heat expansion rate of SiC ceramic part 20 is approximatelyequal to that of the Mo foil 40, thus the SiC ceramic part 20 cansubstantially connect with the Mo foil 40. The heat expansion rate ofthe SUS part 30 is approximately equal to that of the Ti foil 50, thusthe SUS part 30 can substantially connect to the Ti foil 50.Furthermore, the combination of the Mo foil 40 and the Ti foil 50 toform the connecting layer 80 results in a connecting layer 80 having arate of heat expansion that gradually changes from one end to the other.Therefore, the SiC ceramic part 20 is securely connected with the SUSpart 30 and more able to cope with temperature changes.

The composite article 10 manufactured by the present process includesthe SiC ceramic part 20, the SUS part 30 and a multi-layered connectinglayer 80 connecting the SiC ceramic part 20 to the SUS part 30. Theconnecting layer 80 is formed by placing the Mo foil 40 and the Ti foil50 between the SiC ceramic part 20 and the SUS part 30, and then heatingand pressing the SiC ceramic part 20 and the SUS part 30 as previouslydescribed. The various layers of the connecting layer 80 result fromdiffering interaction between the SUS part 30, Mo foil 40, Ti foil 50,and SiC ceramic part 20. In particular, the connecting layer 80includes:

a) a first transition layer 81: The first transition layer 81 mainlyincludes compounds comprising Mo element, C element and Si element, suchas MoC, MoSi, etc. The compounds result from chemical reactions betweenadjacent portions of the SiC ceramic part 20 and Mo foil 40;

b) a Mo layer 82: The Mo layer 82 results from portions of the Mo foil40 that do not react with either the SiC ceramic part 20 or the Ti foil50;

c) a second transition layer 83: The second transition layer 83 islocated between the Mo layer 82 and the Ti layer 84. The secondtransition layer 83 mainly includes compounds comprising Mo element andTi element, and Mo with Ti solid solutions. The compounds and solutionsresulting from chemical reactions between adjacent portions to the Mofoil 40 and Ti foil 50;

d) an Ti layer 84: The Ti layer 84 results from portions of the Ti foil50 that do not react with either the Mo foil 40 or the SUS part 30; and

e) a third transition layer 85: The third transition layer 85 is locatedbetween the Ti layer 84 and the SUS layer 30 and connects the Ti layer84 and the SUS layer 30. The third transition layer 85 mainly includescompounds comprising Ti element and Fe element, and Ti with Fe solidsolutions. The compounds and solutions resulting from chemical reactionsbetween adjacent portions of the Ti foil 50 and the SUS part 30.

The thermal expansion rate of the connecting layer 80 gradually changesfrom a value close to that of the SiC ceramic part 20 (in the area of81) to a value close to that of SUS part 30 (in the area of 85). Thisresults in a composite article 10 well suited to temperature changes dueto the gradual, rather than abrupt, changes in its internal thermalexpansion rates.

Furthermore, the connecting layer 80 of the composite article 10 has nocrack or aperture, and has a smooth surface. The composite article 10has high hardness, high temperature resistance, corrosion resistance andabrasion resistance, a shear strength in a range from about 50 MPa toabout 80 MPa, and a tension strength in a range from about 60 MPa toabout 100 MPa.

It is to be understood that even though numerous characteristics andadvantages of the present embodiments have been set forth in theforegoing description, together with details of assemblies and functionsof various embodiments, the disclosure is illustrative only, and changesmay be made in detail, especially in matters of shape, size, andarrangement of parts within the principles of the present invention tothe full extent indicated by the broad general meaning of the terms inwhich the appended claims are expressed.

1. A process for joining a stainless steel part and a silicon carbideceramic part comprising: providing a SUS part, a SiC ceramic part, a Mofoil and a Ti foil; placing the SiC ceramic part, the Mo foil, the Tifoil, and the SUS part into a mold, the Mo foil and the Ti foil locatedbetween the SiC ceramic part and the SUS part, the Mo foil abutting theSiC ceramic part, the Ti foil abutting the SUS part and the Mo foil;placing the mold into a chamber of an hot press sintering device,heating the chamber and pressing the SUS part, the SiC ceramic part, theMo foil, and the Ti foil at least until the SUS part, the SiC ceramicpart, the Mo foil and the Ti foil form a integral composite article. 2.The process as claimed in claim 1, wherein before pressing, the vacuumlevel inside the chamber is set to about 10⁻³ Pa, argon is fed into thechamber to maintain the chamber with a pressure in a range from about0.3 Mpa to about 0.6 Mpa, the pressing board and the correspondingsupporting board press toward each other at about 10 Mpa to the SiCceramic part and the SUS part.
 3. The process as claimed in claim 1,wherein heating the chamber is heated at a rate of about 10-50° C./min,when the temperature of the chamber reaches to about 300° C., theclamping pressure applied by the pressing board and the correspondingsupporting board steadily increases, until the temperature of thechamber reaches to about 1000-1200° C. and the clamping pressure reachesto about 10-40 Mpa, maintaining the pressure and heat in theirrespective peak ranges for about 30-60 min.
 4. The process as claimed inclaim 1, wherein before formation of the integral composite article, theMo foil has a thickness in a range from about 0.1 mm to about 0.2 mm,and the Ti foil has a thickness in a range from about 0.2 mm to about0.4 mm.
 5. A composite article, comprising: a SiC ceramic part, a SUSpart, and a connecting layer connected the SiC ceramic part to the SUSpart, wherein the connecting layer is formed by placing a Mo foil and aTi foil between the SiC ceramic part and the SUS part, then heating andpressing the SiC ceramic part, the SUS part, the Mo foil and the Tifoil.
 6. The composite article as claimed in claim 5, wherein theconnecting layer orderly includes a first transition layer adjacent theSiC part, a Mo layer, a second transition layer , a Ti layer, and athird transition layer adjacent the SUS part.
 7. The composite articleas claimed in claim 6, wherein the first transition layer locatedbetween the SiC ceramic part and the Mo layer mainly includes compoundscomprising Mo element and C element.
 8. The composite article as claimedin claim 7, wherein the compounds include MoC, MoSi.
 9. The compositearticle as claimed in claim 6, wherein the second transition locatedbetween the Mo layer and the Ti layer mainly includes compoundscomprising Mo element and Ti element, and Mo with Ti solid solutions.10. The composite article as claimed in claim 6, wherein the thirdtransition layer located between the Ti layer and the SUS layer mainlyincludes compounds comprising Ti element and Fe element, and Ti with Fesolid solutions.
 11. A composite article, comprising: a SiC ceramicpart, a SUS part, and a multi-layered connecting layer connected the SiCceramic part to the SUS part, wherein: a first layer of the connectinglayer is adjacent the SiC part and has a thermal expansion rate close tothat of the SiC part; a last layer of the connecting layers is adjacentto the SUS part and has a thermal expansion rate close to that of theSUS part; and the thermal expansion rate of the connecting layersgradually changes from that of the first layer to that of the lastlayer.
 12. The composite article as claimed in claim 11, wherein thelayer of the multi-layered connecting layer comprise: a first layer,adjacent the SiC part and comprising results of chemical reactionsbetween SiC and Mo; a second layer, adjacent the first layer andcomprising Mo; a third layer, adjacent the second layer and comprisingresults of chemical reactions between Mo and Ti; a fourth layer,adjacent the third layer and comprising Ti; and a last layer, adjacentthe fourth layer and the SUS part and comprising results of chemicalreactions between Ti and SUS.